1. Field of the Invention
The present invention relates to an optical disk device, and in particular to an eccentric disk detection apparatus for detecting eccentricity of an optical disk inserted within an optical disk device and controlling revolution of the disk accordingly.
2. Description of the Related Art
The development of high performance personal computers has led to optical disk devices which provide high-speed disk revolution to an optical disk, such as a CD-ROM (Compact Disk-Read Only Memory), CD-R (CD-Recordable), CD-RW (CD-ReWritable), and DVD-RAM (Digital Video Disk-Random Access Memory), inserted within the optical disk device. High-speed disk revolution can cause an eccentric disk, e.g., a disk which is not precisely flat or round, etc., to vibrate. The vibration can adversely affect the personal computer, including the optical disk device, by creating unnecessary noise, by causing failure in the reproduction of the data stored within the optical disk, or by causing failure in writing data to the optical disk.
To prevent the eccentric disk from vibrating, methods have been suggested in order to counteract the eccentricity of the disk. In one method, an automatic balancing device having a circular guide and a sphere rotating over the guide is provided to a spindle motor. During the rotation of the spindle motor, the sphere is automatically positioned in a location where eccentricity is compensated for. Another method calls for the use of an acceleration sensor during revolution of the eccentric disk to detect vibrations.
An unreliable compensation for eccentricity is typically made by using the automatic balancing device due to the slide friction between the sphere and the slide. Further, a non-eccentric disk could be made eccentric by the rotating sphere. Further still, the requirement for a highly precise guide and sphere mechanism can increase the cost of the automatic balancing device. The method utilizing the acceleration sensor also leads to an increase in cost.
A need therefore exists for an eccentric disk detection apparatus for an optical disk device which provides a reliable compensation for eccentricity, protects non-eccentric disks, provides high performance, and is inexpensive.